The present invention relates to a magnetic recording reproducing apparatus and, more particularly, relates to a magnetic recording reproducing apparatus adapted to repeatedly reproduce or read out recorded informations or signals from magnetic tapes or cards.
Heretofore, magnetic recording medium has been widely used as an economical and effective medium for storing informations or signals in the form of tape, disc, card or sheet in various fields including education, entertainment, office labor saving, data storage and the like.
The present invention relates, particularly, to a magnetic tape or card reproducing apparatus of the type wherein the informations or signals in a magnetically recorded tape or card (hereinafter called "master medium") are once magnetically transferred to a unrecorded temporary magnetic medium (hereinafter called "copy medium") by the contact type magnetic transfer method (this is also called "magnetic printing" in the art) and then the transferred informations are repeatedly reproduced from the copy medium with a conventional magnetic reproducing head. As is well known in the art, the contact type magnetic transfer is characterized in that a master medium provided with a magnetic recording surface having a coersive force greater than that of a copy medium is superposed on the copy medium with their magnetic recording surfaces contacting each other and an A-C magnetic field is applied to the contact area of these media. The magnetic field is gradually reduced from a maximum value at which the magnetic recording surface of the copy medium is magnetically saturated or nearly saturated but the recorded signal of the master medium is not substantially effected, so that the hysteresis loop of the copy medium is gradually shifted to minor loops under the influence of the magnetic field of the master medium. It is also well known that the quality of the thusly transferred signals or informations is high.
It has already been proposed to obtain the necessary magnetic field for the transfer or printing by using an AC electromagnet energized from an AC current source. Advantages resulting from the magnetic transfer or printing are that (1) the original signals such as sound signals or image signals recorded on the master medium are not adversely affected nor erased and (2) the signals of the master medium which have been transferred to the copy medium can be repeatedly reproduced. These advantages are important particularly in the field of language training because of the capability of repetitive reproduction of the same sounds of the master medium. For example, in the case where the master medium is in the form of a card having one or more short length of magnetically recorded tracks and the copy medium is in the form of a short length of an endless tape (though the copy medium need not form an endless loop so long as any given point of the copy medium repeatedly arrives at the same reproducing head), the same sounds transferred to the copy medium can be reproduced periodically or repeatedly so long as the copy medium is being driven. In another example, image signals recorded in a master medium can be repeatedly reproduced on a Braun screen from a copy medium which has signals transferred from the master medium. Further, by recording a computer program on a master medium in the form of a card, the same program can be repeatedly produced and applied to input terminals of a computer. Further example would be found in the facsimile field wherein an incoming facsimile image is once recorded on a master medium and then magnetically transferred to an endless copy medium which is then inked with magnetic toners and finally transferred to sheets of paper several times. Thus, the system of this type is effectively utilized in education, entertainment, man power saving and the like.
However, the conventional magnetic recording reproducing apparatus provided with a magnetic transfer arrangement utilizing an AC current source required an electromagnet, an energizing circuit for the electromagnet and an AC current source. For example, a separate oscillating circuit was required in a reproducing apparatus of battery type.
In the conventional compact apparatus wherein a battery is used, there was a defect that a major part of the power is consumed in the oscillating circuit. This made difficult the utilization of the magnetic transfer method in such small portable apparatus.